Thank you Giovanni for your quick reply. I will apply the dipole correction as you suggested.
Paolo 2018-07-25 14:14 GMT-04:00 Giovanni Cantele <[email protected]>: > In you are dealing with asymmetric slabs, dipole correction might be > important. Some adsorbates are just conceived to change the work function > of a material, thus representing dipole layers added on the top of a > surface. The induced dipole can make the vacuum levels in the two sides of > the slab rather different > Giovanni > > Inviato da iPhone > > Il giorno 25 lug 2018, alle ore 20:05, Paolo Costa < > [email protected]> ha scritto: > > Hi Giovanni, > > thanks a lot for your quick reply. > I guess you are definetely right, I did not recognize such error. I will > put right way the calculation of the surface allowing the relax of all the > atoms. I will let you know the results. > > By the way, do you think that the dipole correction is always necessary > for adsorption studies? > > Thanks again. > > Paolo > > 2018-07-25 13:21 GMT-04:00 Giovanni Cantele <[email protected]> > : > >> I cannot visualise your structures at the moment, however one first >> issue, concerning the adsorption energy calculation is that it seems that >> in the system WITOUTH >> the molecule you fixed some Ti/O layers, that are instead free to relax >> in the adsorbed system. As such, the run with the molecule is able to lower >> the total energy >> also by allowing those atoms (a lot!), that were fixed in the other run, >> to change their positions. The result is that the -0.66 Ry contain also the >> energy gain of >> the “free” surface when you let those atoms to relax towards a lower >> energy configuration. So, one first check would bee to see whether the >> atomic positions >> of those atoms changed a lot (for example I see the z of one Ti atom >> equal to 15.819807000 when it is fixed, and 16.095206282 when it is allowed >> to relax, this is a change >> of ~0.3 A -> 2% of the initial coordinate, that summed over all those >> atoms might make a difference!). >> In any case I would try to make a surface (with no molecule) run where >> all atoms are allowed to relax and see how much energy is gained with >> respect to your run. >> >> I could give you more hints tomorrow, if I’m able to visualise the >> structures >> >> Giovanni >> >> -- >> >> Giovanni Cantele, PhD >> >> CNR-SPIN >> c/o Dipartimento di Fisica >> Universita' di Napoli "Federico II" >> Complesso Universitario M. S. Angelo - Ed. 6 >> Via Cintia, I-80126, Napoli, Italy >> >> e-mail: [email protected] <[email protected]> >> [email protected] >> Phone: +39 081 676910 >> Skype contact: giocan74 >> Web page: https://sites.google.com/view/giovanni-cantele >> >> On 25 Jul 2018, at 19:07, Paolo Costa <[email protected]> wrote: >> >> Dear experts, >> >> I got nonsense value of adsorption energy by computing 4-iodoanisole on >> top of TiO2 anastase surface (101). >> By calculating : (Esurface+anisole)-Eanisole-Esurface, I got an >> adsoprtion energy of 0.66 ry (8.98 eV), which is too high. >> Now I am trying to apply the dipole correction to see if this is the >> problem causing an unusual adsorption energy. >> >> In the following link you can find the output files: >> https://www.dropbox.com/sh/edijwg1kyp7gx31/AACD7Up1XIIULbJFToLNqsUra?dl=0 >> >> I would be glad to receive any suggestions to understand the problem. >> >> Thanks. >> >> Paolo >> _______________________________________________ >> users mailing list >> [email protected] >> https://lists.quantum-espresso.org/mailman/listinfo/users >> >> >> >> _______________________________________________ >> users mailing list >> [email protected] >> https://lists.quantum-espresso.org/mailman/listinfo/users >> > > > > -- > Paolo Costa, Ph.D. > Postdoctoral Researcher > Department of Chemistry and Biomolecular Sciences > University of Ottawa > 10 Marie Curie, Ottawa, ON K1N 6N5, Canada > Room number: DRO 326 (D'Iorio Hall) > > _______________________________________________ > users mailing list > [email protected] > https://lists.quantum-espresso.org/mailman/listinfo/users > > > _______________________________________________ > users mailing list > [email protected] > https://lists.quantum-espresso.org/mailman/listinfo/users > -- Paolo Costa, Ph.D. Postdoctoral Researcher Department of Chemistry and Biomolecular Sciences University of Ottawa 10 Marie Curie, Ottawa, ON K1N 6N5, Canada Room number: DRO 326 (D'Iorio Hall)
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